Logging residues and ground vegetation in nutrient dynamics of a clear-cut boreal forest

Abstract

In this thesis are studied the role of decomposing logging residues and developing ground vegetation in nutrient dynamics of a clear-cut area. The main aims were to study how much nutrients are released from logging residues during the first three years after clear-cutting and what is the role of ground vegetation in the retention of nutrients on site after clear-cutting. The study was conducted in eastern Finland in a Norway spruce dominated mixed forest, part of which was clear-cut and part left uncut. The decomposition of Norway spruce (Picea abies (L.) H. Karst.), Scots pine (Pinus sylvestris L.) and silver birch (Betula pendula Roth) logging residues i.e. foliage, fine roots (diameter 2 mm) and branches (diameter 1 cm), were studied using the litterbag method. Above-and below-ground biomass of the ground vegetation was sampled on one uncut plot and two clear-cut plots one year before and five years after clear-cutting.In total, 33 % of the dry mass and C, 49 % of P, 90 % of K and 8 % of Ca were released from logging residues in three years, but there was no net release of N because more N accumulated in the roots and branches than was released from the foliage. The loss of mass, C, P and K was greatest during the first year, whereas there was no net release of Ca until the third year. Most of the released nutrients originated from the foliage. Total ground vegetation biomass and nutrient pools decreased after clear-cutting to one half or even lower, but returned to precutting levels within 4-5 years, and the pools of P and K became even larger. In the first year after clear-cutting more N and Ca accumulated in the logging residues than were stored in the ground vegetation.The results indicate that logging residues are a potential source of the elevated dissolved C and P, K and Ca observed in surface waters soon after clear-cutting, but are not a net source of N during the first three years. The ground vegetation is capable of taking up only a small fraction of the nutrients that are released from logging residues during the first two years after clear-cutting and the decomposing dead ground vegetation is a potential source of leached nutrients. The results suggest that nutrients released from logging residues are initially retained on site primarily through soil processes and microbial immobilization. Solely microbial immobilization in logging residues can initially play a more important role in the retention of N and Ca than the ground vegetation. Ground vegetation, however, recovers rapidly from clear-cutting and it becomes thereafter a significant nutrient sink.

Carbon and nitrogen release from decomposing Scots pine, Norway spruce and silver birch stumps

“…Pine stumps contain 8200-10,900 kg C ha À1 and 11-14 kg N ha À1 , whereas spruce stumps contain 3900-5100 kg C ha À1 and 7-9 kg N ha À1 . The C pool of stumps is relatively large and the pool of N is relatively small compared to the pools in above-ground logging residues (10,000 kg C ha À1 and 80-100 kg N ha À1 in pine stands, and 17,000-20,000 kg C ha À1 and 200-250 kg N ha À1 in spruce stands) (Mä lkö nen, 1975;Hyvö nen et al, 2000;Pumpanen et al, 2004;Palviainen, 2005). Both C and N pools in stumps are rather large compared to the pools in the tree seedlings and ground vegetation on recently clear-cut areas (2000-3000 kg C ha À1 , 30-50 kg N ha À1 ), but small compared to the pools in the soil (60,000-70,000 kg C ha À1 , 1000-2500 kg N ha À1 ) (Liski and Westman, 1997;Finé r et al, 2003;Palviainen, 2005; Palviainen and Finé r, Table 7 The percentage of initial N, C, dry mass and the area specific mass of bark (M b ) remaining in Scots pine, Norway spruce and birch stump wood, stump bark (Bark) without taking fragmentation into account, stump bark (Bark f ) taking fragmentation into account, and in the total stump immediately (0), 5, 10, 20, 30 and 40 years after clear-cutting.…”

Estimation of nutrient removals in stem-only and whole-tree harvesting of Scots pine, Norway spruce, and birch stands with generalized nutrient equations

“…Only a small part of soil nutrients are in a form available for trees (Table 8). The amounts of nutrients removed during the rotation are considerable compared with the plant-available nutrient Table 8 Nitrogen (N), phosphorus (P), potassium (K) and calcium (Ca) deposition (Helmisaari 1995;Ruoho-Airola et al 2003;Piirainen et al 2004), weathering rates (Starr et al 1998;Fisher and Binkley 2000), background leaching from forested areas , the total increase in leaching caused by final cutting (Finér et al 2005; and the total and plant-available N, P, K and Ca pools in the soil in mineral soil (Mälkönen 1974;Helmisaari 1995;Tamminen 1998;Palviainen 2005) and peatland sites (Starr and Westman 1978;Kaunisto and Paavilainen 1988;Laiho 1997;Westman and Laiho 2003) N (kg ha -1 ) P (kg ha -1 ) K (kg ha -1 ) Ca (kg ha -1 ) The effect of final cutting on nutrient leaching can be seen for 10 years after treatment. The data represents nutrient pools and fluxes in Finland a Estimate for the first 6 years after final cutting Eur J Forest Res (2012) 131:945-964 961 pools in the rooting zone.…”

Does harvest residue management influence biomass and nutrient accumulation in understory vegetation of Eucalyptus globulus Labill. plantations in a Mediterranean environment?

“…116-118 and 158;Smith et al, 1997, p. 208), such as those that prevail in Mediterranean environments. However, the structural and functional properties of understory vegetation during early stand development can be beneficial as developing herbs and shrubs contribute to the total annual amount of litter added to stands (Yarie, 1980) and may affect the soil nutrient status (Emmett et al, 1991;Fahey et al, 1991) through nutrient uptake and decreasing water percolation in the soil profile (Gholz et al, 1985;Palviainen, 2005). However, understory vegetation has often been overlooked in biomass, mineral mass and primary production studies of intensive forest plantations (Tremblay and Larocque, 2001;Archer, 2003).…”